An imaginative addition of four structural levels to a Tudor Revival style building at 1915 I St. NW recently won an award from Progressive Architecture magazine for Swaney Kerns, an architecural firm in the District. The magazine cited Reemphasizing rather than disrupting a repetitive roof line" as an imaginative way to expand the four-story building owned by Ronald Cohen. The architectural firm used a Hambro-R lightweight floor system. The builder of Harvey Construction Co. of Rockville.

D.C. Mayor Marion Barry will speak Monday noon to a meeting of the Washington Building Congress at Hogate's.

Former senator John J. Sparkman will receive a gold medal Tuesday from the nation's savings and loan associations, which are marking the 50th anniversary of the founding of the first S&L. The medal is named for Isaac Shallcross, secretary of the first S&L set up in Frankford, Pa., in 1831. Sparkman was selected for the honor because he steered several major housing finance bills through Congress.

The Northern Virginia Board of Realtors will sponsor a housing seminar for non-English-speaking Vietnamese. The session, at which translators will be present, will be Sunday at 1:30 p.m. at Annandale Vietnamese Church. The NVBR plans to conduct other housing seminars for Korean and Spanish-speaking persons in Northern Virginia.

Matthew Deane Maury and Elizabeth Maury Bower recently joined Stuart and Maury Inc., a Washington realty firm in which their father, Deane, is a partner. William Stuart IV and Alice Rhett Stuart are also members of the staff of the firm in which their father, William C. Stuart III, is a partner.

The National Housing Rehabilitation Association, a Washington-based trade group representing professionals in the rehabbing industry, will conduct a seminar in Baltimore March 18-20. Information is available by calling (202) 466-8760.

Lambda Alpha, an international honorary land economics fraternity, recently initiated three new members: writer-editor Kenneth R. Harney, public relations specialist Robert L. Gray and David O. Meeker, executive vice president of the American Institute of Architects.

The Calvert Co., which recently introduced a line of its home in the Promontary Oaks section of Lake Ridge, has announced that seven of its first 22 houses have been sold in the range above $120,000. Meanwhile, Sorenson Construction Corp. has opened its third group of town houses in Lake Ridge, a large community on Lake Occoquan in Prince William County.

Baltimore developer Morton Sarubin, who has a leading role in the rehabilitation of the 2,113-unit Foxchase of Alexandria apartments, will speak March 16 at the Northern Virginia Apartment Association meeting at Westpark-Rosslyn Hotel. Interested persons may call 671-6777 for reservations.

Herbert V. Juul, a former president of the Montgomery County Board of Realtors who formerly operated his own brokerage firm, has joined Bogley Inc. as a vice president and director of sales at the firm's office in Chevy Chase.

A seminar for prospective home buyers will be conducted Tuesday at 7 p.m. in the board room of the Massey building at 4100 Chain Bridge Road in Fairfax under the sponsorship of the county departments of consumer affairs and environmental management. The public is invited. Fairfax County also has a home buyer's shopping guide available by calling 691-2974.

Long & Foster Realtors has, opened a branch office in Annapolis. The firm's 36th branch is located at 2444 Solomon's Island Road, where Lyn Anderson is manager. Anderson also manages the firm's Crofton office. Long & Foster has more than 1,400 sales associates.

Shannon & Luchs, which currently is marking its 75th anniversary, recently opened a residential sales office on Capitol Hill, where Ricki Starrels is the manager. She had been with the firm's office in Georgetown.

Gawen Realty Inc. in the Westover Shopping Center in Arlington, has affiliated with the Century 21 national franchise group. The firm, headed by Perry F. Gawen Jr., has the only Century 21 franchise in Arlington.

Washington developers John Kossow and Lloyd Needle announced that they recently sold eight acres of undeveloped land west of Route 29 in the Fairland area of Montgomery County to the Maryland National Capital Park and Planning Commission for $267,000.